BT-99 Adjustable Comb

Could someone please tell me the advantage of an adjustable comb on a BT-99? I just picked up a 1988 model with a standard stock. I have only been able to shoot it once and did not hit near as many as with my Citori Trap. I did not spend a lot of time at the patterning board to get a good feel for where the POI is. My Citori has a Monte Carlo stock and shoots very high. Do most BT-99 shooters put in the adjustable comb to get more space between the beads and raise the POI to float the bird above the front bead, or is there another reason?